The Pacific oyster (Crassostra gigas) belonging to phylum Mollusca, class Bivalvia, order Ostreoida, family Ostreidae, genus Crassostrea, has advantages of strong adaptability to environment, rapid growth, good taste and high nutritive, and is ranked as the top cultured commercial shellfish with the largest production and the widest distribution in the world. As the most widely farmed shellfish in the world, its industry largely relies on hatchery-produced seed, and all of the broodstock used in hatcheries is sourced from wild populations which have never undergone genetic improvement.
As an economically important trait, the shell color of C. gigas has attracted the interest of geneticists and breeders due to its stable inheritance. In the wild populations of C. gigas, individuals with black, white or golden shell color are common, while no individuals with orange shell color have been found. So far, there is no report on the selective breeding methods of C. gigas with orange left and right shells.